This invention relates to a liquid jetting apparatus, in particular to an ink-jet recording apparatus that can achieve recording of high image-quality mode at a relatively high speed.
In a conventional ink-jet recording apparatus (an example of liquid jetting apparatus), ink (an example of liquid) is jetted from one nozzle for one picture element (one jetting unit area). A volume of the ink jetted from the nozzle is controlled by driving an ink jetting unit (an example of liquid jetting unit) such as a piezoelectric vibrating element provided at a pressure generating chamber communicated with the nozzle with a suitable operating signal.
In addition, in order to position the nozzle with respect to each picture element, a recording head having the nozzle is usually caused to scan in a straight direction with respect to a recording medium (main scan). The recording medium is usually caused to scan in a direction perpendicular to the moving direction (main scanning direction) of the recording head (sub scan).
In order to improve an efficiency of the recording, it is preferable that nozzles are formed in a row in the sub scanning direction. For example, when n nozzles are formed in a row, recording for n raster lines (main scanning lines) can be carried out in one main scan.
Actually, in order to improve image quality of the recording, partly, main scans are overlapped for each raster line in such a manner that a plurality of nozzles pass over each raster line. For example, if a main scan is repeated in a condition shifted downward by n/2 nozzles with respect to the previous main scan, two nozzles can pass over each raster line (however, regarding upper n/2 lines of n raster lines over which nozzles pass at the first main scan and lower n/2 lines of n raster lines over which nozzles pass at the last main scan, only one nozzle can pass over there).
In the case, recording for the same picture element can be carried out by different nozzles. Thus, deterioration of the image quality, which may be caused by positional errors of the nozzles and/or feeding errors during the main scans and the sub scans, can be reduced.
Japanese Patent Laid-Open Publn. No.10-337864 explains in detail that the image quality may be improved more effectively by suitably selecting a sub-scan feed amount.
If ink jetting for the same picture element can be carried out from different nozzles during partly overlapped main scans in order to improve the image quality, recording speed may be lowered by the overlap of the main scans.
The object of this invention is to solve the above problems, that is, to provide a liquid jetting apparatus that can jet liquid with a high quality and at a high speed, such as an ink-jet recording apparatus that can achieve recording with a high image quality and at a high speed, by reducing partial overlap of main scans as much as possible.
The invention is a liquid jetting apparatus comprising: a head member having a plurality of first nozzles, a plurality of second nozzles and a liquid supplying unit that supplies a same kind of liquid to each of the nozzles, the plurality of first nozzles forming a first nozzle row, the plurality of second nozzles forming a second nozzle row that is paired with the first nozzle row; a liquid jetting unit provided at each of the nozzles, the liquid jetting unit causing each of the nozzles to jet the liquid; a holding unit that holds a recording medium; a main scanning unit that causes the head member to move in a main scanning direction relatively to the recording medium; a sub scanning unit that causes the head member to move in a sub scanning direction perpendicular to the main scanning direction relatively to the recording medium; and a controlling unit connected to the liquid jetting unit and the main scanning unit; wherein: there is a slight gap between a moving track of a first nozzle by the main scanning unit and a moving track of a second nozzle paired with the first nozzle by the main scanning unit; and the controlling unit is adapted to control the liquid jetting unit and the main scanning unit in such a manner that a liquid jetting from the first nozzle and a liquid jetting from the second nozzle paired with the first nozzle are carried out in a same main scan, based on jetting data for a same jetting unit area.
According to the invention, since the liquid jetting from the first nozzle and the liquid jetting from the second nozzle paired with the first nozzle are carried out in the same main scan, even if main scans are not repeated, liquid jetting from the two nozzles for the same jetting unit area can be carried out.
In addition, a feature of the invention is that there is the slight gap between the moving track of the first nozzle by the main scanning unit and the moving track of the second nozzle paired with the first nozzle by the main scanning unit. The inventor has found that the beauty on the eye is better when positively adopting the slight gap of the moving tracks than when making the moving tracks to coincide completely.
Preferably, the plurality of first nozzles are formed at substantially regular intervals, the plurality of second nozzles are formed at substantially regular intervals, the intervals between the first nozzles and the intervals between the second nozzles are identical, a number of the first nozzles and a number of the second nozzles are identical so that each of the first nozzles and each of the second nozzles are paired with each other, and the slight gap is less than half or half of an interval of the nozzles in the sub scanning direction.
It is preferable that a volume of the liquid jetted from each of the nozzles at a time is 4 pl or less.
In addition, the controlling unit is also connected to the sub scanning unit, and is adapted to control the liquid jetting unit, the main scanning unit and the sub scanning unit based on a recording mode defined by a sub scan feed amount and information about used nozzles in a main scan. In the case, it is preferable that a recording mode storing unit that stores a plurality of recording modes, and a selecting unit that selects a suitable recording mode among the plurality of recording modes stored in the recording mode storing unit, are provided.
In the case, a control for each pair of nozzles consisting of a first nozzle and a second nozzle paired with the first nozzle can be achieved based on a suitable recording mode.
For example, the liquid supplying unit has a first liquid supplying way and a second liquid supplying way that are adapted to supply the same kind of liquid and that are substantially parallel with each other, the plurality of first nozzles are communicated with the first liquid supplying way, and the plurality of second nozzles are communicated with the second liquid supplying way.
In the case, the head member may be provided with a third liquid supplying way, a fourth liquid supplying way, a plurality of third nozzles communicated with the third liquid supplying way, and a plurality of fourth nozzles communicated with the fourth liquid supplying way, the third liquid supplying way and the fourth liquid supplying way being adjacent to the first liquid supplying way and the second liquid supplying way, being adapted to supply a same kind of liquid and being substantially parallel with each other. In the case, a second liquid jetting unit may be provided at each of the third nozzles and the fourth nozzles for causing each of the third nozzles and the fourth nozzles to jet the liquid. Then, the controlling unit may be also connected to the second liquid jetting unit, and may control the liquid jetting unit and the main scanning unit in such a manner that there is a slight gap between a moving track of a third nozzle by the main scanning unit and a moving track of a fourth nozzle paired with the third nozzle by the main scanning unit, and in such a manner that a liquid jetting from the third nozzle and a liquid jetting from the fourth nozzle paired with the third nozzle are carried out in a same main scan, based on jetting data for a same jetting unit area.
Alternatively, the head member may be provided with a third liquid supplying way, a fourth liquid supplying way, a plurality of third nozzles communicated with the third liquid supplying way, and a plurality of fourth nozzles communicated with the fourth liquid supplying way, the third liquid supplying way being formed between the first liquid supplying way and the second liquid supplying way, the fourth liquid supplying way being adjacent to the second liquid supplying way, the third liquid supplying way and the fourth liquid supplying way being adapted to supply a same kind of liquid. In the case, a second liquid jetting unit may be provided at each of the third nozzles and the fourth nozzles for causing each of the third nozzles and the fourth nozzles to jet the liquid. Then, the controlling unit may be also connected to the second liquid jetting unit, and may control the liquid jetting unit and the main scanning unit in such a manner that there is a slight gap between a moving track of a third nozzle by the main scanning unit and a moving track of a fourth nozzle paired with the third nozzle by the main scanning unit, and in such a manner that a liquid jetting from the third nozzle and a liquid jetting from the fourth nozzle paired with the third nozzle are carried out in a same main scan, based on jetting data for a same jetting unit area.
The paired first nozzle row and second nozzle row may be formed in different recording heads, respectively. That is, the invention is a liquid jetting apparatus comprising: a first head member having a plurality of first nozzles and a liquid supplying unit that supplies a liquid to each of the plurality of first nozzles, the plurality of first nozzles forming a first nozzle row; a second head member having a plurality of second nozzles and a liquid supplying unit that supplies a same kind of liquid as the liquid supplied to each of the plurality of first nozzles to each of the plurality of second nozzles, the plurality of second nozzles forming a second nozzle row that is paired with the first nozzle row; a liquid jetting unit provided at each of the nozzles, the liquid jetting unit causing each of the nozzles to jet the liquid; a holding unit that holds a recording medium; a main scanning unit that causes the respective head members to move in a main scanning direction relatively to the recording medium; a sub scanning unit that causes the respective head members to move in a sub scanning direction perpendicular to the main scanning direction relatively to the recording medium; and a controlling unit connected to the liquid jetting unit and the main scanning unit; wherein: there is a slight gap between a moving track of a first nozzle by the main scanning unit and a moving track of a second nozzle paired with the first nozzle by the main scanning unit; and the controlling unit is adapted to control the liquid jetting unit and the main scanning unit in such a manner that a liquid jetting from the first nozzle and a liquid jetting from the second nozzle paired with the first nozzle are carried out in a same main scan, based on jetting data for a same jetting unit area.
In addition, the liquid jetting unit may be able to cause the first nozzle to jet a or plural first liquid drops and the second nozzle to jet a or plural second liquid drops each of which has substantially the same volume as the first liquid drop. Alternatively, the liquid jetting unit may be able to cause the first nozzle to jet a first liquid drop and the second nozzle to jet a second liquid drop that has a volume different from that of the first liquid drop.
In addition, the invention is a controlling unit for controlling a liquid jetting apparatus including: a head member having a plurality of first nozzles, a plurality of second nozzles and a liquid supplying unit that supplies a same kind of liquid to each of the nozzles, the plurality of first nozzles forming a first nozzle row, the plurality of second nozzles forming a second nozzle row that is paired with the first nozzle row; a liquid jetting unit provided at each of the nozzles, the liquid jetting unit causing each of the nozzles to jet the liquid; a holding unit that holds a recording medium; a main scanning unit that causes the head member to move in a main scanning direction relatively to the recording medium; and a sub scanning unit that causes the head member to move in a sub scanning direction perpendicular to the main scanning direction relatively to the recording medium;
the controlling unit being: adapted to control the main scanning unit in such a manner that there is a slight gap between a moving track of a first nozzle and a moving track of a second nozzle paired with the first nozzle; and adapted to control the liquid jetting unit and the main scanning unit in such a manner that a liquid jetting from the first nozzle and a liquid jetting from the second nozzle paired with the first nozzle are carried out in a same main scan, based on jetting data for a same jetting unit area.
Preferably, the controlling unit is adapted to control the liquid jetting unit in such a manner that the liquid jetting unit causes the first nozzle to jet a or plural first liquid drops and the second nozzle to jet a or plural second liquid drops each of which has a substantially same volume as the first liquid drop.
Alternatively, preferably, the controlling unit is adapted to control the liquid jetting unit in such a manner that the liquid jetting unit causes the first nozzle to jet a first liquid drop and the second nozzle to jet a second liquid drop that has a volume different from that of the first liquid drop.
The above respective controlling units can be materialized by a computer system. A program for materializing the respective controlling units in the computer system, and a storage medium storing the program capable of being read by a computer, should be protected by the application as well.